Modern wells have inflow regions which may have a length up to ten kilometers. In these inflow regions elongate permeable tubulars such as slotted liners, expandable slotted tubulars and/or sandscreens may be arranged which preserve the integrity of the borehole and prevent influx of solids and erosion of the borehole wall during production of oil and/or gas.
However, around these permeable tubulars an annular space of a considerable length may be present or created during production as a result of erosion. This erosion may increase as the eroded annulus may increase in length and width and as a result in some wells the fluid flow through the annulus is equal to or even larger than the production through the interior of the permeable tubular.
Logging procedures which employ downhole spinners that are rotated by the fluid flux inside the tubular will not detect the addition fluid flux through the annulus and may therefore create an Impression that the influx in some regions of the well is smaller than it is in reality. Ultimately this has led to limited production campaigns.
U.S. Pat. No. 4,576,042 discloses a flow basket comprising an umbrella type configuration of petals which are expanded by moving a sleeve relative to a shaft. U.S. Pat. No. 5,033,551 discloses a frusto conical cup which is released downhole by removing a sleeve from the cup after placement of the cup at the top of a wellscreen in a well.
A disadvantage of the known methods is that they require downhole manipulation of well equipment which is a complex and time consuming procedure that is not suitable for installation of a series of seals at short intervals along the length of an inflow region of a well.